third generation computer

architecture A computer built with small-scale integration

integrated circuits, designed after the mid-1960s.

Third generation computers use semiconductor memories in

addition to, and later instead of, ferrite core memory. The

two main types of semiconductor memory are Read-Only Memory

(ROM) and read-and-write memories called Random AccessMemory (RAM).

A technique called microprogramming became widespread and

simplified the design of the CPUs and increased their

flexibility. This also made possible the development of

operating systems as software rather than as hard-wiring.

A variety of techniques for improving processing efficiency

were invented, such as pipelining, (parallel operation of

functional units processing a single instruction), and

multiprocessing (concurrent execution of multiple programs).

As the execution of a program requires that program to be in

memory, the concurrent running of several programs requires

that all programs be in memory simultaneously. Thus the

development of techniques for concurrent processing was

matched by the development of memory management techniques

such as dynamic memory allocation, virtual memory, and

paging, as well as compilers producing relocatable code.

The LILLIAC IV is an example of a third generation computer.

The CTSS (Compatible Time-Sharing System) was developed at

MIT in the early 1960s and had a considerable influence on

the design of subsequent timesharing operating systems.

An interesting contrasting development in this generation was

the start of mass production of small low-cost

"minicomputers".